The present invention relates to a developing device and an image forming apparatus.
In a conventional image forming apparatus such as a printer, a copier, and a facsimile, an image is formed through the following process. First, a charge roller charges a surface of a photosensitive drum. An exposure device such as an LED head exposes the surface of the photosensitive drum to form a static latent image or a latent image thereon. A developing roller attaches a thin layer of toner to the static latent image to form a toner image. A transfer roller transfers the toner image to a sheet or a recording medium, thereby forming an image or printing on the recording medium. A developing device is formed of the photosensitive drum, the charge roller, the developing roller, and so on.
After transferring the toner image, the sheet is transported to a fixing device, so that the fixing device fixes the toner image to the sheet.
In the conventional image forming apparatus described above, the developing device is provided with a developing device main body and a toner cartridge detachably attached to the developing device main body. The toner cartridge supplies toner to the developing device main body through a toner supply opening thereof. When the toner cartridge is removed from the developing device main body, toner sticking to a surrounding area of the toner supply opening may drop, thereby making inside the image forming apparatus dirty. To this end, the toner supply opening tends to have a small opening and be formed at a center portion of each of the toner cartridge and the developing device main body.
As described above, in the conventional developing device, the toner supply opening is formed at a center portion of each of the toner cartridge and the developing device main body. Accordingly, toner tends to drop only at a specific location inside the developing device. Especially, in the developing device before being used or after toner is detected to be a low level, when the toner cartridge is attached to the developing device main body and supplies toner, a large amount of toner is supplied at a center portion of the developing device main body, and a small amount of toner is supplied at both side portions thereof. Accordingly, it is difficult to uniformly supply toner along a longitudinal direction of the developing device, that is, a width direction of the image forming apparatus. As a result, a resultant image tends to have a difference in darkness in a width direction of a sheet, thereby deteriorating image quality.
In view of the problems described above, an object of the present invention is to provide a developing device and an image forming apparatus, in which it is possible to solve the problems in the conventional developing device. In particular, it is possible to prevent an image from having a difference in darkness in a width direction of a recording medium, and to improve image quality.
Further objects and advantages of the invention will be apparent from the following description of the invention.